Landing: 2791799fe11f

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Project / Subsystem

gcc / gcc/optimization

Date

2026-08-06

Author

Kyrylo Tkachov

Commit

2791799fe11f886736869e3aff093e0c14fb10b8

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: gcc/optimization
patch_id: —
commit_hash: 2791799fe11f886736869e3aff093e0c14fb10b8
source_type: github
headline: pair-fusion: Verify that a fused pair really is adjacent
tldr: Fixes pair-fusion optimization to prevent incorrect code generation by ensuring fused memory accesses are truly adjacent.
author: Kyrylo Tkachov
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • optimization
• correctness
• code generation
• gcc
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/2791799fe11f886736869e3aff093e0c14fb10b8
date: 2026-08-06T00:00:00.000Z

The pair-fusion optimization pass has been corrected to accurately verify that fused memory accesses are indeed adjacent. Previously, when using MEM_EXPR base offsets, the pass could incorrectly identify non-adjacent memory accesses as adjacent, leading to silent generation of wrong code. This fix adds a check to compare offsets relative to a common base register, preventing such misinterpretations and ensuring correctness.